Study to Evaluate Safety, of NextraTM in Surgery to Fuse the Proximal-interphalangeal- Joints

Overview

Hammertoe deformity is the most common deformity of the lesser toes. It primarily comprises flexion deformity of the proximal interphalangeal (PIP) joint of the toe, with hyperextension of the metatarsophalangeal (MTP). Etiologies of hammertoe deformity include a foot in which the second ray is longer than the first, MTP synovitis and instability, inflammatory arthropathies, neuromuscular conditions, and ill-fitting shoe wear. When a foot's second ray is longer than the first and shoe wear does not fit correctly, flexion of the PIP joint occurs to accommodate the shoe. This length difference also causes MTP synovitis to develop from overuse of the second MTP joint. Attenuation of the collateral ligaments and plantar plate result, and the MTP joint hyperextends and may even progress to dorsal subluxation or dislocation (see image below). Rheumatoid arthritis causes hammertoe deformity by progressive MTP joint destruction, leading to MTP joint subluxation and dislocation. With all 3 of these etiologies, the extensor digitorum longus (EDL) tendon gradually loses mechanical advantage at the PIP joint, as does the flexor digitorum longus (FDL) tendon at the MTP joint. The intrinsic muscles fire and sublux dorsally, as the MTP hyperextends. They now extend the MTP joint and flex the PIP joint, as opposed to their usual functions of flexing the MTP joint and extending the PIP joint.

Device Description: Nextra implant is an anatomical 2-piece designed implant with 10° angulation with a locking fusion mechanism. The self-centering, metaphysis screw design allows a stable and secure relationship of the proximal and middle phalanges. The compression with progressive tightening approximates the bone surfaces for a controlled fusion. Pre-clinical Data: The Nextra Implant has been used to create fusions between the proximal and middle phalanges of the 2nd, 3rd. or 4th. toe. Clinical Experience: The NextraTM Implant has been used in humans as an implant to reduce hammertoe and contracture deformities. 2\. STUDY OBJECTIVES: The primary objective is to evaluate the post-market safety and performance of NextraTM in the reduction of post-operative pain symptoms in hammertoes and demonstrate the efficacy of the implant to securely stabilize bone surfaces to be fused as to be compared to K-wire fixation. 3\. STUDY DESIGN: General Design: Preoperative and post-operative factors will be assessed in the evaluation of efficacy and safety.